Shoot Initiation from Carnation Shoot Apices Frozen to -196{degrees}C

Aseptically excised shoot apices from Dianthus caryophyllus were frozen to -196 degrees C and subsequently thawed to room temperature. Survival rates as high as 33 percent, determined by callus formation, growth, or chlorophyll formation, are reported; plant formation has been observed.     

乳牛胚胎冷冻保存技术和受胎率的研究

51枚可用胚胎,依次通过含有3.3%,6.7%,10%甘油的抗冻剂处理后,装入26支塑料细管,置于冷冻仪上,以每分钟降低1℃的速率从室温降-6.5℃,平衡5 min 后进行诱发植冰,又平衡5 min,再以每分钟降低0.3℃的速率降至-36℃,平衡10 min 后直接投入-196℃的液氮中保存。先后从液氮中取出16支冷冻保存不同时间(1,8,9,10,28,29,31,32,62天)的冷冻胚胎塑料细管,用30℃温水进行快速解冻,分3步脱除甘油,回收32枚胚胎,其中可用胚胎22枚分别移植给11头受体牛,结果4头妊娠(妊娠率为36.3%)并顺利生下4头发育正常的犊牛。     

Biological damage from intranuclear tritium: DNA strand breaks and their repair

Isotopic decay in tritiated thymidine in the DNA of frozen (-196 degrees C) Chinese hamster cells causes breaks in DNA strands to accumulate at a rate of 2.1 breaks per decay. After DNA is thawed the tritium-induced breaks repair rapidly with a half-time of 15 minutes at 37 degrees C. In comparison to breakage by x-rays, the efficiency of DNA strand breakage by tritium is equivalent to 0.48 rad per decay. This dose per decay is close to that predicted by simple dosimetric considerations (0.38 rad per decay) for irradiation by the beta particles from tritium.     

Field measurement of slow metamorphic reaction rates at temperatures of 500 degrees to 600 degrees C

High-temperature metamorphic reaction rates were measured using strontium isotopic ratios of garnet and whole rock from a field site near Simplon Pass, Switzerland. For metamorphic conditions of cooling from 612 degrees +/- 17 degrees C to 505 degrees +/- 15 degrees C at pressures up to 9.1 kilobars, the inferred bulk fluid-rock exchange rate is 1.3(-0.4)(+1.1) x 10(-7) grams of solid reacted per gram of solid per year, several orders of magnitude lower than laboratory-based estimates. The inferred reaction rate suggests that mineral chemistry may lag the evolving conditions in Earth's crust during mountain building.     

Chloroplast DNA from tobacco leaves

DNA from tobacco leaf chloroplasts was isolated as a single component with a buoyant density in CsCl of 1.702 compared to 1.697 for nuclear DNA. 5-Methylcytosine is present in nuclear DNA but absent in chloroplast DNA. Chloroplast DNA, with a guanine-cytosine content of 43 percent, has a melting temperature of 86 degrees C and renatures completely on slow cooling, whereas nuclear DNA ( melting temperature, 84 degrees C; guanine-cytosine content, 40 percent) does not renature. About 9 percent of the total DNA in tobacco leaves is chloroplast DNA representing about 4.7 xX 10-(15) gram of DNA per chloroplast with a molecular weight of approximately 4 xX 10(7).     

Magnetic properties of lunar sample 10048-22

The natural remanent magnetization (3.7 x 10(4) electromagnetic units per cubic centimeter) and the susceptibility per cubic centimeter (6.3 x 10(-13)) of an 18.5-gram breccia specimen were determined with instrumentation and techniques currently used in paleomagnetism. The relatively low magnetic stability of the rock in the earth's field and in alternating demagnetizing fields precludes considering it as a reliable carrier of paleomagnetism. A magnetic balance study yields an unusually high Curie temperature (750 degrees C) which is possibly diagnostic of metallic Fe containing less than 5 percent nickel. The estimated relative abundance of the iron in the sample is about 0.5 percent.     

Kaolinite Synthesis at 25{degrees}C

The addition of quercetin, an organic flavone (C(15)H(10)O(7)), to aqueous solutions containing silica and aluminum and adjusted to final pH's from 6.5 to 8.5 produced a 1 : 1 alumninosilicate precipitate which, after 6 to 16 months of aging in solution at 25 degrees C, contained as much as 5 percent well-formed kaolinite plates. Similar solutions containing no organic material produced relatively amorphous precipitates with the same composition and stability (standard free energy of formation = -897+/-1 kilocalories per mole) but with substantially smaller amounts of crystaline material even after 2 years of aging.     

长毛兔胚胎冷冻保存和移植

从9只供体母兔(长毛兔)获得了235枚3日龄胚胎,以0.3℃/min 的递减速度进行冷冻并保存于液氮(-196℃)中44～163h。胚胎取出后直接投入32℃水浴中解冻,得到145枚形态正常的胚胎,分5批移植于15只土种受体母兔。获得13只健康的长毛仔兔。     

Weakening of dunite by serpentine dehydration

A shear press has been used to determine the mechanical behavior of serpentinized dunite and forsterite at normal pressures to 50 kilobars, temperatures to 900 degrees C; and strain rates from 10(-1) to 10(-4) per second. The shear strength of dunite, containing less than 5 percent by volume of serpentine, is reduced by at least 30 percent as the temperature is raised from 300 degrees to 520 degrees C. Abundant kink bands develop at normal pressures above 35 kilobars at 27 degrees C and at lower pressures as the temperature is increased.     

Luminescence and thermoluminescence induced by bombardment with protons of 159 million electron volts

We have observed a red luminescence, qualitatively similar to that of enstatite achondrites, in unsorted fines, their separated mineral phases, and rock chips. The energy efficiency of the plagioclase fraction is approximately 1 percent. At -196 degrees C the effect is enhanced by a factor between 1 and 2. All fractions except ilmenite exhibit blue thermoluminescence with a glow peak near -135 degrees C and an energy efficiency approximately 4 x 10(-6). Unlike the thermoluminescence of terrestrial and meteoritic material, it is nonrepeatable even after annealing at 200 degrees C. Similar thermoluminescence is seen in rock chips, but in unsorted fines it is masked by the opaque fractions.     

Carbon nanotubes with temperature-invariant viscoelasticity from -196 degrees to 1000 degrees C

Viscoelasticity describes the ability of a material to possess both elasticity and viscosity. Viscoelastic materials, such as rubbers, possess a limited operational temperature range (for example, for silicone rubber it is -55° to 300°C), above which the material breaks down and below which the material undergoes a glass transition and hardens. We created a viscoelastic material composed from a random network of long interconnected carbon nanotubes that exhibited an operational temperature range from -196° to 1000°C. The storage and loss moduli, frequency stability, reversible deformation level, and fatigue resistance were invariant from -140° to 600°C. We interpret that the thermal stability stems from energy dissipation through the zipping and unzipping of carbon nanotubes at contacts.     

速冻中低温保护剂浓度对小鼠胚胎发育的影响

用快速冷冻方法，冷冻小鼠的２－细胞胚、４－细胞胚、８－细胞胚、桑椹胚和囊胚，低温保护液分别含有０．５，１．５，２．５，４ｍｏｌ／Ｌ丙二醇，含１０％的犊牛血清和０．２５ｍｏｌ／Ｌ蔗糖，对于８－细胞以前的小鼠胚胎，快速冷冻保存时丙二醇的浓度在２．５ｍｏｌ／Ｌ和４ｍｏｌ／Ｌ时效果较好，随着小鼠早期胚胎（囊胚以前）的发育，抗低温冷冻的能力加强。     

Crystal Structure of Krypton Difluoride at -80{degrees}C

Krypton difluoride is tetragonal, space group P4(2)/ mnm, with two linear molecules per unit cell aligned in planes perpendicular to the tetrad axes. The alignment alternates by 90 degrees between successive planes. The kryptonfluorine bond distance is 1.89 +/- 0.02 angstroms.     

Kyanite-Sillimanite Equilibrium at 750{degrees}C

Reversal of the kyanite-sillimanite inversion has been accomplished hydrothermally at 750 degrees C. The inversion pressure at 750 degrees C is 8.1 +/- 0.4 kilobars. The calculated pressuretemperature slope at this point is 17.7+/- 1.0 bars per degree celsius. Geologically, this result seems more plausible than previous estimates of the location of the boundary. When combined with other work on the relative stability of andalusite, the data indicate that andalulsite cannot be stable at a pressure greater than 4.2 kilobars.     

Xenon Hexafluoride: Structure of a Cubic Phase at -80{degrees}C

The crystal structure of a cubic phase of composition XeF(6) has been determined at -80 degrees C. There are no simple molecules in the complex structure which involves 1008 atoms distributed over 1600 positions per unit cell. Ions of XeF(5)+ and F- are associated in tetrameric and hexameric rings of point group symmetries 4 and 32, respectively. The structure contains right-and left-handed conformations of both tetramers and hexamers. The handedness of the tetramers is dis-ordered but the orientation is ordered. The handedness of the hexamers is ordered but the orientation is disordered.     

包被方法对小鼠半胚冷冻效果的影响

将小鼠囊胚一分为二后,采用血清-琼脂法(A),透明带-琼脂法 (B)和双层透明带法(C)包被半胚。在RPE冷冻仪的控制下,对包被半胚进行冷冻。解冻后将360枚半胚进行体外培养。A,B,C三组的半胚发育率分别为69.2％(83/120),67.5％(81/120)和60％(72/120)。将12对在冷冻前用A法包被的解冻半胚移植于6只假孕母鼠,结果有3只妊娠,共产半胚鼠8只,其中3对为同卵双生。实验证明,本研究建立的血清-琼脂包被法操作简便,效果良好,便于应用,是一种较理想的包被半胚新方法。     

Helium isotope effect in solution in water and seawater

The isotope effect in the solution of helium in water from 0 degrees to 40 degrees C has been determined by microgasometric measurements of the solubilities of pure helium-3 and helium4. At 0 degrees C helium-3 is less soluble than helium-4 in both distilled water and sea-water by 1.2 percent. The observed fractionation factor is 0.988+/-0.002 at 0 degrees C and appears to decrease with increasing temperature at the rate of 0.0001 per degree Centigrade, although the existence of this trend is of limited statistical certainty. The measured isotope effect is in agreement with the ratio of helium-3 to helium-4 in surface ocean water reported by Clarke, Beg, and Craig.     

Thermophilic ostracod: aquatic metazoan with the highest known temperature tolerance

The upper lethal temperature for an ostracod of the genus Potamocypris collected from a thermal stream ranged from 49 degrees C for incubation of more than 5 hours to 55.75 degrees C for 1-minute incubations. Field collections were held at 35 degrees C for less than 24 hours before experimental incubations. Calculated temperatues for 50 percent mortality for 60, 40, 20, 10, 5, and 1 minute of exposure were 50.44 degrees , 50.96 degrees , 51.43 degrees , 52.03 degrees , 52.77 degrees , and 55.12 degrees C, respectively.     

Crystal Structure of the Solid Electrolyte(C5H5NH) Ag5I6 at -30{degrees}C

The crystal structure of pyridinium hexaiodopentaargentate, (C(5)H(5)NH) Ag(5)l(6), is unique among those of the halide and chalcogenide solid electrolytes in that face-sharing iodide octahedra as well as face-sharing tetrahedra and face-sharing between octahedra and tetrahedra provide the paths for silver ion transport. There are two formula units in a hexagonal cell, space group P6/mcc (D6h(2)). At -30 degrees C, the lattice constants are a = 11.97 +/- 0.02, c = 7.41 +/- 0.01 A. The structure has three sets of sites for the silver ions. At -30 degrees C two of these sets are apparently filled with the ten silver ions per unit cell, while the third set of tetrahedrally coordinated general positions is empty. Therefore, the conductivity at this temperature is limited by the thermal excitation of the silver ions into the empty tetrahedra.     

Synthesis of lipid during photosynthesis by phytoplankton of the southern ocean

Assimilation of carbon-14 labeled bicarbonate into photosynthetic products was measured at four stations in the Southern Ocean. Phytoplankton populations incorporated as much as 80 percent of the fixed carbon into lipid under conditions of low temperatures (-0.2 degrees to -1.8 degrees C) and low light intensities. At higher temperatures (+0.3 degrees to +0.8 degrees C) and higher light intensities, incorporation into lipid accounted for less than 20 percent of the fixed carbon, synthesis of polysaccharide and protein being more prominent.